/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.netbeans.modules.editor.lib;

/**
 * This is an implementation of wcwidth() and wcswidth() (defined in
 * IEEE Std 1002.1-2001) for Unicode.<br>
 *
 * <a href="http://www.opengroup.org/onlinepubs/007904975/functions/wcwidth.html">
 * http://www.opengroup.org/onlinepubs/007904975/functions/wcwidth.html</a><br>
 * <a href="http://www.opengroup.org/onlinepubs/007904975/functions/wcswidth.html">
 * http://www.opengroup.org/onlinepubs/007904975/functions/wcswidth.html</a></p>
 *
 * <p>In fixed-width output devices, Latin characters all occupy a single
 * "cell" position of equal width, whereas ideographic CJK characters
 * occupy two such cells. Interoperability between terminal-line
 * applications and (teletype-style) character terminals using the
 * UTF-8 encoding requires agreement on which character should advance
 * the cursor by how many cell positions. No established formal
 * standards exist at present on which Unicode character shall occupy
 * how many cell positions on character terminals. These routines are
 * a first attempt of defining such behavior based on simple rules
 * applied to data provided by the Unicode Consortium.</p>
 *
 * <p>For some graphical characters, the Unicode standard explicitly
 * defines a character-cell width via the definition of the East Asian
 * FullWidth (F), Wide (W), Half-width (H), and Narrow (Na) classes.
 * In all these cases, there is no ambiguity about which width a
 * terminal shall use. For characters in the East Asian Ambiguous (A)
 * class, the width choice depends purely on a preference of backward
 * compatibility with either historic CJK or Western practice.
 * Choosing single-width for these characters is easy to justify as
 * the appropriate long-term solution, as the CJK practice of
 * displaying these characters as double-width comes from historic
 * implementation simplicity (8-bit encoded characters were displayed
 * single-width and 16-bit ones double-width, even for Greek,
 * Cyrillic, etc.) and not any typographic considerations.</p>
 *
 * <p>Much less clear is the choice of width for the Not East Asian
 * (Neutral) class. Existing practice does not dictate a width for any
 * of these characters. It would nevertheless make sense
 * typographically to allocate two character cells to characters such
 * as for instance EM SPACE or VOLUME INTEGRAL, which cannot be
 * represented adequately with a single-width glyph. The following
 * routines at present merely assign a single-cell width to all
 * neutral characters, in the interest of simplicity. This is not
 * entirely satisfactory and should be reconsidered before
 * establishing a formal standard in this area. At the moment, the
 * decision which Not East Asian (Neutral) characters should be
 * represented by double-width glyphs cannot yet be answered by
 * applying a simple rule from the Unicode database content. Setting
 * up a proper standard for the behavior of UTF-8 character terminals
 * will require a careful analysis not only of each Unicode character,
 * but also of each presentation form, something the author of these
 * routines has avoided to do so far.</p>
 *
 */
public class WcwdithUtil {

	/** sorted list of non-overlapping intervals of non-spacing characters.*/
	/* generated by "uniset +cat=Me +cat=Mn +cat=Cf -00AD +1160-11FF +200B c" */
	static final int[][] nonSpacingCharTable = {
		{0x0300, 0x036F}, {0x0483, 0x0486}, {0x0488, 0x0489},
		{0x0591, 0x05BD}, {0x05BF, 0x05BF}, {0x05C1, 0x05C2},
		{0x05C4, 0x05C5}, {0x05C7, 0x05C7}, {0x0600, 0x0603},
		{0x0610, 0x0615}, {0x064B, 0x065E}, {0x0670, 0x0670},
		{0x06D6, 0x06E4}, {0x06E7, 0x06E8}, {0x06EA, 0x06ED},
		{0x070F, 0x070F}, {0x0711, 0x0711}, {0x0730, 0x074A},
		{0x07A6, 0x07B0}, {0x07EB, 0x07F3}, {0x0901, 0x0902},
		{0x093C, 0x093C}, {0x0941, 0x0948}, {0x094D, 0x094D},
		{0x0951, 0x0954}, {0x0962, 0x0963}, {0x0981, 0x0981},
		{0x09BC, 0x09BC}, {0x09C1, 0x09C4}, {0x09CD, 0x09CD},
		{0x09E2, 0x09E3}, {0x0A01, 0x0A02}, {0x0A3C, 0x0A3C},
		{0x0A41, 0x0A42}, {0x0A47, 0x0A48}, {0x0A4B, 0x0A4D},
		{0x0A70, 0x0A71}, {0x0A81, 0x0A82}, {0x0ABC, 0x0ABC},
		{0x0AC1, 0x0AC5}, {0x0AC7, 0x0AC8}, {0x0ACD, 0x0ACD},
		{0x0AE2, 0x0AE3}, {0x0B01, 0x0B01}, {0x0B3C, 0x0B3C},
		{0x0B3F, 0x0B3F}, {0x0B41, 0x0B43}, {0x0B4D, 0x0B4D},
		{0x0B56, 0x0B56}, {0x0B82, 0x0B82}, {0x0BC0, 0x0BC0},
		{0x0BCD, 0x0BCD}, {0x0C3E, 0x0C40}, {0x0C46, 0x0C48},
		{0x0C4A, 0x0C4D}, {0x0C55, 0x0C56}, {0x0CBC, 0x0CBC},
		{0x0CBF, 0x0CBF}, {0x0CC6, 0x0CC6}, {0x0CCC, 0x0CCD},
		{0x0CE2, 0x0CE3}, {0x0D41, 0x0D43}, {0x0D4D, 0x0D4D},
		{0x0DCA, 0x0DCA}, {0x0DD2, 0x0DD4}, {0x0DD6, 0x0DD6},
		{0x0E31, 0x0E31}, {0x0E34, 0x0E3A}, {0x0E47, 0x0E4E},
		{0x0EB1, 0x0EB1}, {0x0EB4, 0x0EB9}, {0x0EBB, 0x0EBC},
		{0x0EC8, 0x0ECD}, {0x0F18, 0x0F19}, {0x0F35, 0x0F35},
		{0x0F37, 0x0F37}, {0x0F39, 0x0F39}, {0x0F71, 0x0F7E},
		{0x0F80, 0x0F84}, {0x0F86, 0x0F87}, {0x0F90, 0x0F97},
		{0x0F99, 0x0FBC}, {0x0FC6, 0x0FC6}, {0x102D, 0x1030},
		{0x1032, 0x1032}, {0x1036, 0x1037}, {0x1039, 0x1039},
		{0x1058, 0x1059}, {0x1160, 0x11FF}, {0x135F, 0x135F},
		{0x1712, 0x1714}, {0x1732, 0x1734}, {0x1752, 0x1753},
		{0x1772, 0x1773}, {0x17B4, 0x17B5}, {0x17B7, 0x17BD},
		{0x17C6, 0x17C6}, {0x17C9, 0x17D3}, {0x17DD, 0x17DD},
		{0x180B, 0x180D}, {0x18A9, 0x18A9}, {0x1920, 0x1922},
		{0x1927, 0x1928}, {0x1932, 0x1932}, {0x1939, 0x193B},
		{0x1A17, 0x1A18}, {0x1B00, 0x1B03}, {0x1B34, 0x1B34},
		{0x1B36, 0x1B3A}, {0x1B3C, 0x1B3C}, {0x1B42, 0x1B42},
		{0x1B6B, 0x1B73}, {0x1DC0, 0x1DCA}, {0x1DFE, 0x1DFF},
		{0x200B, 0x200F}, {0x202A, 0x202E}, {0x2060, 0x2063},
		{0x206A, 0x206F}, {0x20D0, 0x20EF}, {0x302A, 0x302F},
		{0x3099, 0x309A}, {0xA806, 0xA806}, {0xA80B, 0xA80B},
		{0xA825, 0xA826}, {0xFB1E, 0xFB1E}, {0xFE00, 0xFE0F},
		{0xFE20, 0xFE23}, {0xFEFF, 0xFEFF}, {0xFFF9, 0xFFFB},
		{0x10A01, 0x10A03}, {0x10A05, 0x10A06}, {0x10A0C, 0x10A0F},
		{0x10A38, 0x10A3A}, {0x10A3F, 0x10A3F}, {0x1D167, 0x1D169},
		{0x1D173, 0x1D182}, {0x1D185, 0x1D18B}, {0x1D1AA, 0x1D1AD},
		{0x1D242, 0x1D244}, {0xE0001, 0xE0001}, {0xE0020, 0xE007F},
		{0xE0100, 0xE01EF}
	};

	/**
	 * Returns defined column width of a Unicode character.
	 *
	 * <p>The following functions defines the column width of an ISO 10646
	 * character as follows:</P>
	 *
	 * <ol>
	 * <li>The null character (U+0000) has a column width of 0. </li></li>
	 *
	 * <li> Other C0/C1 control characters and DEL will lead to a return
	 *      value of -1.</li>
	 *
	 * <li> Non-spacing and enclosing combining characters (general
	 *      category code Mn or Me in the Unicode database) have a
	 *      column width of 0.</li>
	 *
	 * <li> SOFT HYPHEN (U+00AD) has a column width of 1.</li>
	 *
	 * <li> Other format characters (general category code Cf in the Unicode
	 *      database) and ZERO WIDTH SPACE (U+200B) have a column width of 0.</li>
	 *
	 * <li> Hangul Jamo medial vowels and final consonants (U+1160-U+11FF)
	 *      have a column width of 0.</li>
	 *
	 * <li> Spacing characters in the East Asian Wide (W) or East Asian
	 *      Full-width (F) category as defined in Unicode Technical
	 *      Report #11 have a column width of 2.</li>
	 *
	 * <li> All remaining characters (including all printable
	 *      ISO 8859-1 and WGL4 characters, Unicode control characters,
	 *      etc.) have a column width of 1.</li>
	 * </ol>
	 * 
	 * @param codePoint the character (Unicode code point) in question.
	 * @return column width of the character.
	 */
	public static int wcwidth(int codePoint) {
		/* test for 8-bit control characters */
		if (codePoint == 0) {
			return 0;
		}

		if (Character.isISOControl(codePoint)) {
			return -1;
		}

		/* binary search in table of non-spacing characters */
		if (binarySearch(codePoint)) {
			return 0;
		}

		/* if we arrive here, ucs is not a combining or C0/C1 control character */
		return 1 + ((codePoint >= 0x1100 &&
				(codePoint <= 0x115f ||                         /* Hangul Jamo init. consonants */
				codePoint == 0x2329 || codePoint == 0x232a ||
				(codePoint >= 0x2e80 && codePoint <= 0xa4cf &&
				codePoint != 0x303f) ||                         /* CJK ... Yi */
				(codePoint >= 0xac00 && codePoint <= 0xd7a3) || /* Hangul Syllables */
				(codePoint >= 0xf900 && codePoint <= 0xfaff) || /* CJK Compatibility Ideographs */
				(codePoint >= 0xfe10 && codePoint <= 0xfe19) || /* Vertical forms */
				(codePoint >= 0xfe30 && codePoint <= 0xfe6f) || /* CJK Compatibility Forms */
				(codePoint >= 0xff00 && codePoint <= 0xff60) || /* Fullwidth Forms */
				(codePoint >= 0xffe0 && codePoint <= 0xffe6) ||
				(codePoint >= 0x20000 && codePoint <= 0x2fffd) ||
				(codePoint >= 0x30000 && codePoint <= 0x3fffd))) ? 1 : 0);
	}

	/**
	 * Searches if the codepoint is in the range of non-spacing character table.
	 *
	 * @param codePoint the current character (Unicode code point) in question.
	 * @return true if it is a non-spacing character, otherwise false.
	 */
	private static boolean binarySearch(int codePoint) {
		int max = nonSpacingCharTable.length - 1;

		if (codePoint < nonSpacingCharTable[0][0] || codePoint > nonSpacingCharTable[max][1]) {
			return false;
		}

		int min = 0;
		while (max >= min) {
			int mid = (min + max) / 2;
			if (codePoint > nonSpacingCharTable[mid][1]) {
				min = mid + 1;
			} else if (codePoint < nonSpacingCharTable[mid][0]) {
				max = mid - 1;
			} else {
				return true;
			}
		}

		return false;
	}

	/**
	 * Controls how to count the column width.
	 */
	public interface CountingAlgorithm {
		/**
		 * Returns the calculated column count result.
		 *
		 * @param codePoint the current character (Unicode code point) in question.
		 * @param count the calculated result before counting current character.
		 * @param w default column width of current character.
		 * @return the calculated result. Return -1 to end the whole counting process.
		 */
		public int calculate(int codePoint, int count, int w);
	}

	/**
	 * A counting algorithm that would ends the whole counting and return -1 when
	 * an ISO control character is met.
	 */
	public final static CountingAlgorithm ISO_CONTROL_TERMINATE = new CountingAlgorithm() {

		public int calculate(int codePoint, int count, int w) {
			if (w < 0) {
				return -1;
			}
			return count + w;
		}

	};

	/**
	 * A counting algorithm that would ignore an ISO control character.
	 */
	public final static CountingAlgorithm ISO_CONTROL_IGNORE = new CountingAlgorithm() {

		public int calculate(int codePoint, int count, int w) {
			if (w < 0) {
				w = 0;
			}
			return count + w;
		}

	};

	/**
	 * Returns column width of a string.
	 *
	 * @param s the string to count.
	 * @param countingAlgorithm counting algorithm.
	 * @return column width of the questioned string.
	 */
	public static int wcswidth(String s, CountingAlgorithm countingAlgorithm) {
		char[] array = s.toCharArray();
		int count = 0;
		for (int i = 0; i < array.length; ++i) {
			int codePoint;
			if (Character.isHighSurrogate(array[i])) {
				codePoint = Character.toCodePoint(array[i], array[i + 1]);
				i++;
			} else {
				codePoint = array[i];
			}
			int w = wcwidth(codePoint);
			count = countingAlgorithm.calculate(codePoint, count, w);
			if (count < 0) {
				return count;
			}
		}

		return count;
	}

}
